Have you upgraded your SketchUp in the past? Other Mac users have seen similar issues to what you’re seeing when they’ve upgraded SketchUp versions. Apparently, SketchUp has an issue on the Mac during install where it doesn’t clean up or delete all the old files which causes a conflict that affects the CabWriter plugin. One of the other beta testers found a fix for it. See this forum thread:
After cleaning everything up, you can go ahead and re-install the version of SketchUp you want to use. Can you give it a try and see if it fixes the issue? Also, you want to make sure you’re using the latest CabWriter release from May 23rd.